;just GetOpenFileName -> this prg wants to delete file, I have no idea why... ?

include 'win32ax.inc'
macro   m2m     dest,src
{ 
        push    src 
        pop     dest 
}

.data

  szFilter              db "All Files",0,"*.*",0,0 
  szTitle               db "Select file to delete",0 



  hInstance             dd ? 
  hFileHandle           dd ? 
  hFileSize             dd ? 
  hFileMap              dd ? 
  hFileView             dd ? 

  szFilePath            rb 260
  luna    rb sizeof.OPENFILENAME     ; reservation for structure         OPENFILENAME

.code
proc  _openfile, lpFileBuffer ,.ofs

        lea edi,[.ofs]

        mov     [edi+OPENFILENAME.lStructSize],sizeof.OPENFILENAME 
        mov     [edi+OPENFILENAME.hwndOwner],HWND_DESKTOP 
        m2m     [edi+OPENFILENAME.lpstrFile],[lpFileBuffer] 
        mov     [edi+OPENFILENAME.nMaxFile],MAX_PATH 
        mov     [edi+OPENFILENAME.lpstrFilter],szFilter 
        mov     [edi+OPENFILENAME.nFilterIndex],1 
        mov     [edi+OPENFILENAME.lpstrFileTitle],NULL 
        mov     [edi+OPENFILENAME.nMaxFileTitle],NULL 
        mov     [edi+OPENFILENAME.lpstrInitialDir],NULL 
        mov     [edi+OPENFILENAME.Flags],OFN_EXPLORER+OFN_FILEMUSTEXIST+OFN_HIDEREADONLY 
        mov     [edi+OPENFILENAME.lpstrTitle],szTitle 

        invoke  GetOpenFileName,edi
endp

  start:

        invoke  GetModuleHandle,NULL
        or      eax,eax 
        jz      .exit_prog 

        mov     [hInstance],eax


        stdcall _openfile,szFilePath,luna
        or      eax,eax 
        jz      .exit_prog

.exit_prog:
        invoke  ExitProcess,NULL



.end start
    

      m2m     edi,[.ofs]
    

Second, inside your _openfile procedure you should use